onScrollUp property

This is the semantic equivalent of a user moving their finger across the
screen from bottom to top. It should be recognized by controls that are
vertically scrollable.

VoiceOver users on iOS can trigger this action by swiping up with three
fingers. TalkBack users on Android can trigger this action by swiping
right and then left in one motion path. On Android, onScrollUp and
onScrollLeft share the same gesture. Therefore, only on of them should
be provided.